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6.3 Sonic MBES Receive (Normal Operation Mode)
The Projector is comprised of composite ceramics that convert electrical energy to acoustic energy.
The composite ceramics, in the Receive Module, convert the reflected acoustic energy back to
electrical energy. The small electrical voltage, generated by the ceramics, is amplified and then
passed onto the receivers. The output of the receivers goes directly to the Wet Controller board in
the Receive Module.
In general, the receive pattern is 130° (normal bathymetry survey) in the across-track. The along-
track pattern depends on the frequency; from 23° at 400 kHz to 40° at 200 kHz.
Figure 141: Receive pattern with Transmit pattern
The Wet Controller board contains the FPGA that performs the beamforming and bottom detection
operation; time tags the data; and formats the sonar data for output back up to the SIM. The
bathymetry data is output as a Range and Bearing (from the sonar head’s acoustic centre) for each
beam. Other outputs include TruePix™ / Snippets, beamformed imagery and water column data.
The output of the Wet Controller board is sent through the deck lead, to the SIM’s Gigabit switch
and onto the data collection computer through one of the SIM’s external RJ45 connections.
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